From bgreenbaum@SECURITYFOCUS.COM Wed Jan 31 00:11:23 2001
From: Ben Greenbaum
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To: BUGTRAQ@SECURITYFOCUS.COM
Date: Tue, 30 Jan 2001 18:33:03 -0700
Subject: [BUGTRAQ] Microsoft Security Bulletin (MS01-004) (fwd)
---------- Forwarded message ----------
Date: Mon, 29 Jan 2001 22:21:39 -0800
From: Microsoft Product Security
To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM
Subject: Microsoft Security Bulletin (MS01-004)
The following is a Security Bulletin from the Microsoft Product Security
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Title: Patch Available to Eliminate New Variant of "File
Fragment Reading via .HTR" Vulnerability
Date: 29 January 2001
Software: IIS 4.0 and 5.0
Impact: File Reading
Bulletin: MS01-004
KB Article: Q285985 (available soon)
Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/ms01-004.asp
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Issue:
======
This vulnerability involves a new variant of the "File Fragment
Reading via .HTR" vulnerability, previous variants of which were
discussed in Microsoft Security Bulletins MS00-031 and MS00-044. Like
the original variants, this one could enable an attacker to request a
file in a way that would cause it to be processed by the .HTR ISAPI
extension. The result of doing this is that fragments of server-side
files like .ASP files could potentially be sent to the attacker.
There is no capability via the vulnerability to add, change or delete
files on the server, or to access a file without permissions.
Mitigating Factors:
====================
- Microsoft has long recommended that customers disable the .HTR
functionality unless there is a business-critical reason not to.
Customers who have followed this recommendation would be at no
risk from this vulnerability.
- Best practices strongly recommend against ever including sensitive
information in .ASP and other server-side files. If this
recommendation has been followed, there would be no sensitive
information in the file to compromise.
- The .HTR processing would tend to strip out the sections of the
file most likely to contain sensitive information.
- There would need to be zeros located fortuitously in memory to
serve as null terminators for the data.
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